Rhizobacterial mediated antimetabolites and their significant effect on human pathogens

Background: The emergence of antibiotic resistant bacteria is increasing globally. Therefore, new strategies and exploration of new metabolites are need of the day to combat various diseases. The aim of the current study is to isolate the rhizobacterial strains from medicinal plants to examine their antibacterial activity against human pathogens.Methods: The total 239 rhizobacterial isolates were screened with agar plug and well diffusion methods, characterized biochemically and identified by Bergey’s manual scheme. In chemical screening, metabolic extracts of rhizobacterial isolates were separated in thin layer chromatography (TLC) and further identified by HPLC. The ability of rhizobacterial strains for optimum metabolite production was checked in vitro under different environmental conditions.Results: Results showed that 31% isolates had antibacterial activity against Bacillus cereus, Bacillus subtilis, E. coccus, E. coli, Salmonella, Klebsiella, Staphylococcus aureus ATCC20737, Staphylococcus aureus ATCC25923 and Neisseria. Gonorrhea ATCC19424, methicillin resistant Staphylococcus aureus 1, methicillin resistant Staphylococcus aureus 6 and methicillin resistant Staphylococcus aureus 8. Maximum rhizobacterial strains showed best antibacterial activity at 35ᵒC and at pH7. ST5 strain showed significant results against E. coli ETCC and methicillin resistant Staphylococcus aureus-7 (25mm zone of inhibition). The bands of ST5 and ST2 extracts on a TLC plate were detected at Rf value 4.7 and 4.8 respectively. In HPLC, different peaks at different retention times with maximum peak at 2.90 and 2.92 indicating the production of antimetabolites.Conclusion: These rhizobacterial isolates are valuable inputs in natural consortium to produce specific antibacterial metabolites. Demonstrating the structure and purification of these bioactive compounds may enhance the antimicrobial activities which further can be helpful in development of antibiotics.Keywords: Antibiotics; Rhizobacteria; Antimicrobial agents; MRSA; HPL